Apparatus and method for a cellular freeway emergency telephone service

ABSTRACT

A self-contained cellular emergency roadside call box is disclosed without the use of external telephone lines. The call box is solar powered with battery storage and comprises a controller coupled to a cellular transceiver. The controller is also coupled to a solar array and battery which is recharged through the controller. The call box communicates through a radio-telephone link established by the cellular transceiver to a cellular telecommunication system. The cellular telecommunication system includes a call site controller and mobile telephone switching terminal. Each call box comprises a plurality of status subcircuits for monitoring conditions such as battery condition and transmitter status. The call box communication and the status are processed by a micro processor which generates appropriate commands required by the cellular transceiver. Information can be transmitted bidirectionally between each of the call boxes and the communication applications processor. An interactive flow of information is exchanged with the call box and the functional condition is monitored. 
     The questions raised in reexamination request No. 90/002,066, filed Jun. 25, 1990, have been considered and the results thereof are reflected in this reissue patent which constitutes the reexamination certificate required by 35 U.S.C. 307 as provided in 37 CFR 1.570(e).

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to the field of cellular telephone equipment andin particular to solar powered telephone call boxes using a cellulartelephone system to radiotelephonically communicate from a plurality offixed roadside sites.

2. Description of the Prior Art

Emergency roadside call boxes have become increasingly important andproductive elements in providing roadside security and emergencyassistance in the metropolitan areas in the United States and throughoutthe world. Originally, such roadside emergency call boxes were hardwiredto conventional telephone land lines. However, the installation of suchtelephone land lines substantially escalates the installation andmaintenance costs of such emergency roadside telephone boxes. In orderto overcome this limitation, the prior art devised emergency telephonecall boxes which use a radio transmission link for communications.Cannalty et al., "Emergency Communications System", U.S. Pat. No.3,939,417; and Wisniewski, "Emergency Calling System", U.S. Pat. No.3,492,581 show such systems. Power for the these call boxes is providedby a rechargeable battery included within their housings. However, suchprior art battery operated systems either required the units to becoupled to a source of electrical power for trickle-charging or requiredthe periodic replacement or recharging of the battery packs throughmobile roadside service. Again, although savings were realized ininstallation costs by using battery powered units, the maintenance orservice costs of such systems often prohibited their use.

Furthermore, in the past radiotelephone communications within geographicareas were realized using a process based on a single transmitter andantenna. This method of communication limits the number of calls thatcan be placed in a geographic area and limits the size of the area thatcan be covered with a given amount of equipment. However, with therecent advent of cellular telephone technology, these limitations, whichwere characteristic of the prior art single transmitter systems, nolonger exist.

Therefore, what is needed is a design and method of using a radio linkedemergency call box which is adaptable to cellular telephone technologyand which is characterized by low installation and service costs.

BRIEF SUMMARY OF THE INVENTION

The invention is a system for providing an emergency call box servicecomprising a plurality of emergency call boxes, wherein each cell boxfurther comprises: a controller; a cellular transceiver coupled to thecontroller; a battery coupled to the controller for providing power tothe controller and transceiver; and a solar array for generating powercoupled to the controller for recharging the battery. Also included inthe system is a cellular telecommunications subsystem inradio-telecommunication with each of the plurality of emergency callboxes. A communication applications processor is coupled to the cellulartelecommunications subsystem for processing data received in part fromthe plurality of emergency call boxes. The communications applicationsprocessor communicates through the cellular telecommunications subsystemwith selected ones of the plurality of emergency call boxes. By reasonof this combination of elements the plurality of emergency call boxescan be installed and maintained at low cost and are capable ofarbitrarily programmable interactive operations.

The system further comprises interoffice local telephone exchangescoupled to the communication applications processor whereincommunication between the plurality of emergency call boxes can beselectively coupled to the local telephone exchanges under control ofthe communication applications processor.

The controller comprises a plurality of status subcircuits. Each statussubcircuit monitors a predetermined status parameter of thecorresponding call box.

The system further comprises a circuit for selectively communicating thepredetermined parameters as monitored by the plurality of statussubcircuits to the communication applications processor. The parametersmonitored by the status subcircuits include battery power level, and thephysical condition of the corresponding call box indicative in part ofwhether call box has been struck.

The controller further comprises a circuit for receiving and processinginformation from the communication applications processor to initiateoperations in the controller.

The controller still further comprises a circuit for adjusting thevolume of transmitted and received audio information.

The controller has a timing mechanization included within its digitalcircuitry. The timer provides the capability to measure predeterminedelapsed time periods. The timer mechanism is used in the following ways:

(1) To limit each call to a maximum duration (e.g. 10 minutes;

(2) To terminate a call if there is no conversation for a predeterminedperiod of time (e.g. one minute); and

(3) To cause each call box to automatically initiate a call and toreport its operational status on a periodic basis (e.g. once every 24hours).

In the event that the telephone handset is left off the hook, theautomatic time out will terminate the call and will thus save batterypower. Should this occur, the call box is automatically reactivated andanother emergency call is placed should the hook switch be operated tothe on-hook status followed by an off-hook status.

Stated in yet another way the invention is an emergency roadside callbox comprising: a controller; a cellular transceiver coupled to andcontrolled by the controller; a battery for powering the controllercoupled to the controller and transceiver; and a solar array coupled tothe controller for recharging the battery. By reason of this combinationof elements an emergency roadside call box can be installed andmaintained at low cost.

The controller comprises a plurality of status subcircuits formonitoring corresponding selective parameters of the controller, and acircuit for interrogating the plurality of status subcircuits foroperationally responding to the parameters as monitored by the statussubcircuits.

The plurality of the subcircuits comprise at least a subcircuit formonitoring a user request for emergency transmission, battery condition,presence of a communication transmitted to and from the call box,physical integrity of the call box.

The call box further comprises a circuit for selectively communicatingthe corresponding plurality of parameters of the call box to an off-siterecipient.

The call box still further comprises a circuit for receiving informationgenerated off-site and a circuit for initiating an operation of the callbox in response to the received off-site information.

The controller comprises a circuit for conserving power from the batterywhen an emergency communication is not desired, and a circuit foradjusting audio gain for audio information transmitted and received bythe call box.

The invention can still further be characterized as a method in anemergency roadside call box, where the call box is battery powered andcoupled through a radio-telecommunication link to a cellulartelecommunication system and communication applications processor. Themethod comprises the steps of reading a plurality of call box statusparameters. Next follows the step of selectively performing a remedialroutine in response to the step of reading the plurality of statusparameters dependent upon the condition of each corresponding parameter.Thereafter follows the step of selectively entering an emergency callroutine wherein a cellular telecommunication transceiver within the callbox is powered up and bidirectional voice communication is establishedthrough the cellular telecommunication system to the communicationapplications processor. By virtue of this method, remotely poweredemergency call boxes in radio-telecommunication with the communicationapplications processor are operationally maintained.

The invention can still further be characterized as an apparatus incombination with a cellular radiotelephone for generating informationcompatible with the cellular radiotelephone in a solar powered emergencycall box. The invention comprises a first circuit for determining aplurality of status conditions relating to the emergency call box; asecond circuit for controlling power usage of the emergency call box tominimize power usage; and a third circuit for processing the statusconditions determined by the first circuit and responsive to at leastthe status conditions controlling the second circuit. The third circuitalso selectively bidirectionally generates and receives cellularradiotelephone compatible signals under programmable control. The thirdcircuit is coupled to the first and second circuit and to the cellularradiotelephone.

The invention is best understood in the context of an illustrativeexample as shown in the following drawings wherein like elements arereferenced by like numerals.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a system in which the call boxincorporating the invention is included.

FIG. 2 is a front elevational depiction of the call box as installed ata roadside site.

FIG. 3 is a side elevational view of the call box of FIG. 1.

FIG. 4 is a block diagram of including the controller in the call boxand its associated system elements.

FIG. 5 is a schematic diagram of status subcircuits included in thecontroller.

FIG. 6 is a schematic diagram of another status subcircuit.

FIG. 7 is a schematic diagram of a circuit to read the status data.

FIG. 8 is a schematic diagram of a programmable microprocessorincorporated in the controller.

FIG. 9 a schematic diagram of decoder circuit used to communicatebetween the microprocessors on the controller.

FIG. 10 is a schematic diagram of a circuit for coupling signals betweenthe transceiver and one of the microprocessors on the controller.

FIG. 11 is a schematic diagram of an audio level adjust circuit whichcan be controlled by a remote central processor.

FIG. 12 is a flow diagram illustrating the operation of the controller.

The invention and its various embodiments may be better understood bynow turning to the following description.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Before considering the detailed circuitry in the cellular call box andits method of operation, first generally consider the environment inwhich the call box is used and how it is utilized during normaloperation.

Turn now to FIG. 1. When an emergency occurs along a roadside, theaffected user will locate the nearest emergency call box, generallydenoted by reference numeral 10. The user will lift the handset whichwill cause call box 10 to automatically dial a preprogrammed number tothe freeway emergency telephone system control center. The call istransmitted via a radio link to a local cell site transceiver 12 over aselected one of 21 channels according to which channel is the strongestcellular channel available. This selection of communication channels bytransceiver 12 and mobile telephone switching office 14 is well known inthe art of cellular communications and will not be further described.Local cell site transceiver 12 is connected with a mobile telephoneswitching office 14 by wireline trunks. Mobile telephone switchingoffice 14, which is an automatic terminal, then provides call boxidentity confirmation and predialed access to the control center, whichincludes a communications applications processor generally denoted byreference numeral 16. Mobile telephone switching office 14 can alsoconnect call box 10 to a conventional telephone switching exchange 15 inresponse to commands from the control center so that three partytelephone conference calls can be provided or the call from call box 10simply handed off to another telephone station.

The incoming calls will be uniquely identified with a specific emergencycall box. The identification will then be used to access a data base andall information corresponding to that call box will be retrieved in theapplications processor 16. An automatic call distributor 18 will connectthe incoming call to an available operator at a communicationsapplications processor (CAP) sort center 20. A human operator answersthe call and the communication which to this point has been digital willbe followed by voice communication. Specific call box information willbe displayed on the screen in response to an automatic call distributorprocessor 22 coupled with a master processor 24 which causes specificinformation to be brought up from the data base to the appropriatesupport station 20. Such information includes the location of the callbox, nearest access roads, local terrain and appropriate local emergencynumbers. Support station 20 and master processor 24 interactivelycommunicate so that all subsequent actions which are undertaken by theoperator can be logged for archival, management and planning use.Archival discs 26 are coupled to and controlled by master processor 24for mass data storage.

Turn now specifically to call box 10 as shown in FIG. 2 in frontelevational view and in FIG. 3 in side elevational view. Call box 10 isa completely self-contained unit requiring no connection with externalpower lines or telephone cables. Box 10 is solar powered, is designedfor use with a cellular telephone system, and is characterized bylow-cost installation with quick repair or replacement.

As shown in FIGS. 2 and 3, call box 10 comprises a housing 28 mounted ona road standard 30. Housing 28 includes the call box controller, radiotransceiver and battery described and shown diagrammatically in thefollowing Figures. The three watt radio transceiver is coupled to aconventional collinear antenna 32 with 3 dB of isotropic gain mounted onthe top of standard 30. Also mounted with antenna 32 is a solar panel34. Solar panel 34 as described below is coupled to circuitry withinmain housing 28 and is used to recharge the batter included within thehousing. In particular, solar array 34 is made of thirty-four matchedsilicon solar cells with peak power rated at 10.5 watts. The panel isglass laminated and held in a metal frame to protect it from dirt,moisture and impact. Approximately 2.2 watt hours per day is generatedon the average by the solar panel 34, which is equivalent to the amountof power for 45 minutes of constant air time, generally estimated to beequal four to five average roadside emergency calls. Standard 30 iscoupled to a ground anchor 36 to embed it into the site. Ground anchor36 and standard 30 are coupled together by brake plate 38 seen in FIG. 2so that, if a vehicle collides with standard 30, brake plate 38 willbend, retain standard 30 to the ground anchor 36, and allow standard 30to be folded over instead of being snapped over the hood and thrustthrough the windshield of the oncoming vehicle. Standard 30 is generallyU-shaped so that the coupling antenna and power lines between housing 28and solar array 34 antenna 32 are laid in the U-shaped channel ofstandard 30 and can be covered or weather sealed by protective plate 35.The entire unit therefore comprises a sealed and weatherproof assembly.

The three watt cellular transceiver enclosed within main housing 28 is aconventional Motorola cellular transceiver sold under the trademark,DYNA-TAK 2000. The details of operation of the transceiver are onlyimplicitly included in this description and will not be expresslydiscussed except to the extent necessary for a fully illustrateddescription. Further details of the transceiver of the illustratedembodiment can be found in the published user's manual, entitled DYNAT.A.C., Cellular Mobile Telephone, 800 MHz Transceiver, available fromMotorola Technical Writing Services at 1301 E. Algonquin Rd.,Schaumburg, Ill. 60196 which is expressly incorporated herein byreference.

Although details of the transceiver are incidental to the invention, ageneral description is provided here for completeness of explanation.First consider the receive circuitry of the transceiver. In thetransceiver discussed in the illustrated embodiment, radio signals in apredetermined range are selected by a 6-pole bandpass filter. Themodulated receive signal is then passed to a preamplifier. A 3-polefilter, which further bandpass filters the receive signal, is coupled tothe output of the preamplifier. A first mixer is coupled to the 3-polefilter. An injection signal is generated by a receiver synthesizer andmixes with the receive signal to provide a first IF signal. The IFsignal is then coupled to an IF board. The IF signal (45 MHz) is coupledto a buffer amplifier whose output is coupled to a 2-pole crystal filterwhich passes the signal on to a second buffer amplifier. The output ofthis buffer amplifier is coupled to a second 2-pole filter. The outputof the second 2-pole filter is coupled to a circuit which includes asecond mixer, an IF amplifier, a receiver signal strength indicator, anda FM detector. A second conversion and detection is executed in thiscircuit and its output is an audio signal which is coupled to anaudio/logic board. On the audio/logic board the audio receive signal isconditioned in a conventional manner.

An audio signal from the handset is coupled to the radio via a transmitaudio hybrid on the audio/logic board. This hybrid comprises a bufferand a 300 Hz to 3 kHz bandpass filter. The output from the bandpassfilter of the transmit audio hybrid is fed to a 2:1 compressor comprisedof by one half of a single IC compander located on the audio/logicboard. The compander dynamically condenses the audio signal, which isexpanded 1:2 by the cell site controller to the original dynamic range.The output of the compressor is fed back into the transmit audio hybrid,which contains circuitry for preemphasis, limiting, filtering, audiomuting, and a summing amplifier to combine the transmit audio signalwith data, supervisory audio tones and other control signals beforeoutputting the signal to the synthesizer digital board. The transmitaudio signal is coupled to the modulation input of a sidestep VCO on thesynthesizer board. The output of the VCO, a modulated 30 MHz signal, iscoupled to a buffer whose output is coupled to one input of a sidestepmixer. The injection input on the mixer is provided with a signal whichis an output frequency doubled from the receive VCO. The output of themixer is a modulated RF signal. The RF signal is then coupled through a3-pole filter, and amplifier before being coupled to a RF poweramplifier.

The frequency synthesizer comprises a receiver VCO, a synthesizerdigital board, and an exciter board. The operating frequencies in theradio are all derived from the receiver VCO phase-locked loop. This iscomprised of a dual modulus prescaler, a programmable PLL IC, a chargepump, loop filter, and receiver VCO hybrid. This loop is controlled by achannel select line from the logic circuitry which serially loads thechannel select data into the programmable PLL IC. One output of thereceiver VCO goes through a frequency tripler and is fed to the injectordoubler hybrid used in the first mixer of the RF receive circuitry. Theother output from the receive VCO is coupled to a frequency doubler onthe exciter boar and serves as the input signal to the sidestep mixer.

Further details and schematics of all the above circuitry can be foundin the Motorola User's manual referenced above.

The transceiver signals which are referenced most often in thedisclosure of the illustrated embodiment are the handset signals. Thehandset includes a cradle microprocessor which provides an interfacebetween the microprocessor of the handset and the microprocessor of thetransceiver logic unit. Digital communication is effectuated through thedigital signals C DATA, T DATA and R DATA. Data carried by the busconvention include keypad and fluorescent display information for thehandset, display information for the cradle control/indicator board, andother various control signals and commands between the control unit andtransceiver logic unit. Only the more relevant of these signals will bediscussed below. Logic gates are provided in conjunction with the bussignals to gate either timing information or data depending on the stateof a control line INT SELECT. The handset processor uses this circuitryto determine if the information on the T DATA line is actual data ormerely a timing pulse. C DATA and T DATA, or C DATA and R DATA (thechoice depending on the direction of information flow) will be logicalcomplements during data transmission. When they are not so related, theywill signify timing information, i.e. the reset or idle states.Communications with these signals is on a three wire bidirectional bus.Data is communicated in an address-then-data serial word format. At thebeginning of communication the bus direction is established. Duringmessage transmission each data state is followed by an idle state with areset state entered after the last data bit of the message. Furtherdetails of the bus protocol are described in the Motorola User's manualreferenced above.

Keypad data is communicated from the handset via column and row signalswhich are then used with an internal look-up table to identify thekeypad button which was pushed.

Handset 40 is diagrammatically depicted in FIG. 2. No further detaileddiscussion of the transceiver will be undertaken except to such extentas such details affect the operation of the cellular call box controlleralso included in housing 28. The controller is a single board circuitwhich can be easily removed from a modular pin connector and a new boardinserted for easy field service. The controller comprises the logic andcircuitry necessary to control the entire operation of call box 10.Turning to FIG. 4, a diagrammatic depiction of the elements within callbox 10 is shown. Cellular call box controller 42 serves as the centralunit to which solar array 34, battery 46 and any additional call boxswitches or input/output functions 48 are coupled. Similarly, cellulartransceiver 44 is coupled to controller 42 and antenna 32 in turn iscoupled to cellular transceiver 44.

Before describing the circuitry of controller 42, consider first thefunctions which controller 42 performs. Included among, but not limitedto these functions are:

(1) controlling operation sequences for user friendly adaptation;

(2) automatically powering the transceiver when handset 40 is lifted;

(3) automatically dialing the preprogrammed number or alternatively anyone of a plurality of numbers corresponding to one of a correspondingplurality of activated switches or buttons (not shown in the Figures);

(4) automatically powering down after a preset, preprogrammed timeperiod or after hang-up of handset 40;

(5) controlling and adjusting necessary voltage level changes in audioand logic circuits;

(6) controlling and regulating all timing functions to integrate thevarious portions of the assembly;

(7) controlling and regulating the recharging rates from solar array 34;

(8) controlling all power for the entire assembly depicted in FIG. 4 ina manner designed for the most efficient conservation and use of power;

(9) interfacing to transceiver 44; and

(10) providing necessary logic and interface for optional controllerfunctions and future enhancements such as slow scan video or specializeddata links.

Controller 42 is built around a microprocessor 118 described inconnection with FIG. 8. A number of signals indicative of the status ofcall box 10 are coupled to a data bus 116 as described in FIG. 7 towhich microprocessor 118 is coupled and are generated by a plurality ofstatus circuits described in FIGS. 5 and 6. Microprocessor 118 generatesa number of discrete control signals through a decoder 130 (FIG. 8) forthe control of these status circuits and control signals which areutilized in a decoder tree in FIG. 9 to provide key pad and othercellular control signals to cellular telephone transceiver 44.

Input and output to cellular telephone transceiver 44 is completelyeffectuated by the keypad signals shown coupled to the input/output busin FIG. 9 and by the digital signals, C DATA, T DATA, and R DATAdescribed below in connection with microprocessors 118 and 166. Cellulartelephone transceiver 44 communicates with microprocessor 118 through asecond or interfacing microprocessor 166 described in FIG. 10. Bothmicroprocessors 118 and 166 control the transmit and receive audio levelcontrol circuitry shown in FIG. 11. The overall operation ofmicroprocessor 118 is summarized by the flow chart of FIG. 12.

Turn now to FIG. 5 wherein the operation of these functions can beprovided by the circuitry illustrated. FIGS. 5-7 are schematics ofseveral circuits which are controllably used to sense a number of statusconditions of call box 10. For example, the charged condition of battery46, the physical integrity of call box 10, the presence of informationon the communication channel, the status of handset 40, and thecondition of the transmitter are all monitored and selectively reportedby means of the circuitry which will now be described in connection withthe following Figures.

Consider first the battery condition circuit depicted in FIG. 5. Battery46 is coupled to node 50. A conventional voltage regulator, generallydenoted by reference numeral 52 converts the 13 volts D.C. to 5 voltsfor use throughout the logic circuitry as indicated. The battery voltageat node 50 is monitored by a conventional zener diode 54. If the voltageis sufficient, transistor 56, whose input is coupled to the anode ofdiode 54, will be biased on and its output coupled through twoinverters, collectively denoted by reference numeral 58, to the setinput terminal SD, of a clocked latch 60. The output, Q, of latch 60 isprovided with the signal, inverted LO BAT (low battery), which isutilized in subsequent circuitry as described below. Whenever LO BAT istrue, a predetermined low battery voltage or state of battery dischargedis indicated. The clock input, CP, of latch 60 is provided with asignal, SET LO BAT (set low battery). Latch 60 is cleared by a signal,CL LO BAT (clear low battery), coupled to the clear terminal, CD, oflatch 60.

Consider now the circuitry in FIG. 5 which monitors the physicalcondition of call box 10, namely whether standard 30 is down on theground. A mercury tilt switch 62 is coupled between the five volt supplyand ground and is normally closed. However, should the pole be struck,or otherwise tilted, switch 62 will open as shown in FIG. 5. When switch62 opens, a high or true signal will be coupled to the set terminal, SD,of clocked latch 64 whose output Q, is the signal, DWN (down),representing that the pole is down. The clock input, CP, is the signal,SET DWN (set down), and latch 64 is cleared at its clear terminal, CD,by the signal CL DWN (clear down).

Turn now to the circuitry in FIG. 5 used to monitor the status of the rftransmitter. When transceiver 44 is turned on, 9 volts are applied tonode 72. This in turns on transistor 74 whose output is coupled throughinverter 76 to provide the signal, inverted TRANS PWR (transmitterpower), indicative that the transmitter is powered up. Again, TRANS PWRis used in circuitry to be described below as a status signal indicativeof the operation of call box 10.

Consider now the circuitry in FIG. 5 used to selectively power up the rftransmitter, which as a primary power user, is normally off. A signal,RLY ON (relay on), generated by means described below, is applied to aDarlington pair, generally denoted by reference numeral 94, toselectively energize a relay 96. When relay 96 is energized in responseto RLY ON, the 13 volts of power at node 50 is coupled through contacts98 to a plurality of power terminals IGN SENSE, BAT PLUS, BAT PLUSTRANSCEIVER POWER, utilized elsewhere in the circuitry as an operativemeans of powering up transceiver 44. These power voltages are particularto the Motorola transceiver assumed in the illustrated embodiment andare thus not further discussed here.

Turning your attention to the circuitry of FIG. 6 consider now thestatus of the operation of handset 40. The audio portion of the signalfrom handset 40 is coupled through capacitor 78 to a peak-to-peakdetector, generally denoted by reference numeral 80. The output ofpeak-to-peak detector 80 is coupled through a buffer, generally denotedby reference numeral 82, to the set input, SD, of clocked latch 86. Theoutput Q, of latch 86 is the signal, BSY (busy), which indicates thatinformation, conversation, or at least an audio signal of some sort isbeing provided to handset 40. The clock input, CP, of latch 86 is thesignal SET BSY (set busy) and latch 86 is cleared at its clear terminal,CD, by the signal, CL BSY (clear busy).

The means for originating various status signals now having beendescribed, the primary status signal, namely the lifting of the handsetoff its hook switch, can be considered. Conventional telephone hookswitch 100 in FIG. 5 senses the lifting of handset 40. One terminal ofthe switch 100 is coupled to ground and the remaining terminal iscoupled to a debounce NAND gate latch, generally denoted by referencenumeral 102. The output of latch 102 is the status signal, OFF LAT (offlatch), which is also used as a clocking signal for clocked latch 106.The input, D, of latch 106 is coupled to the 5-volt power supply so thatupon receipt of a clock pulse, OFF LAT, output Q of latch 106, thesignal, OFF HK (off hook), goes high. Latch 106 is cleared at is clearterminal, CD, by a signal, CL OFF HK (clear off hook). Thus once thehandset has been taken off hook, the circuitry will be able to rememberthat this has occurred even if placed back on hook until latch 106 iscleared by program control through CL OFF HK. This allows the program torecognize that a call was attempted and to enter a call ready status fora predetermined time regardless of the actual hook condition.

Turn now to FIG. 7. The various status signals described in connectionwith FIGS. 5 and 6, OFF HK, DWN, LO BAT, BSY, TRANS PWR, and OFF LAT areeach provided as inputs to an encoder 114. The output of encoder 114 iscoupled to a data bus 116 as a parallel 8-bit word described in moredetail in connection with FIG. 8. The remaining portions of thecircuitry of FIG. 7 will be described below.

Turning to FIG. 8, the encoded word in data bus 116, which isdiagrammatically shown throughout the circuitry as appropriate, iscoupled to inputs B0-B7 of microprocessor 118, which is the operationalprogrammed microprocessor of controller 42. Microprocessor 118 in theillustrated embodiment is a Motorola 6805 CMOS device which ischaracterized by very low power consumption. Microprocessor 118 isclocked by a conventional external crystal controlled clocking circuit,generally denoted by reference numeral 119. The program formicroprocessor 118 is stored within an external EPROM memory 120. Memory120 is accessed by microprocessor 118 through terminals B0-B7 andA8-A12, which provide a thirteen-bit access word. Terminals B0-B7 areused during the first half cycle of processor 118 as the lower eightbits of the address and during the second half cycle as a datainput-output. Therefore, during the memory fetch, the lower eight bitsof the address are coupled through data bus 116 to a bit latch 122 underthe control of the address strobe signal from terminal AS of processor118. Thereafter, all thirteen bits of the address are coupled to addressbus 124. The address inputs A0-A10 of memory 120 are thus coupled toaddress bus 124 and memory 120 enabled by address bits A11 and A12through NAND gate 126 and strobed by the output of NAND gate 128. Memory120 is selectively strobed in a read or write cycle according tosoftware control through the read/write terminal, inverted R/W, and datastrobe terminal DS of microprocessor 118 which are provided as theinputs to NAND gate 128.

Upon power up and reset the internal address register of microprocessor118 is set at the highest address of 2K EPROM memory 120. The program isstored in two kilobytes of memory. Thus A12 and A11 are provided as theinputs to NAND gate 126 whose output is coupled to the inverted chipenable terminal, CE. Thus the two highest address bits serve as anaddress enable. The control and timing of microprocessor 118 withrespect to memory 120 is conventional and will not be further detailedbeyond that just outlined. At any rate, memory 120 is appropriatelystrobed and stored information is then read from outputs Q0-Q7 onto databus 116. The signals data strobe, DS, and the read/write signal, R/W,from microprocessor 118 are similarly coupled to the inputs of NAND gate128, whose output then serves as an output enable signal coupled to theinverted output enable terminal of EPROM memory 120. Thus, data frommemory 120, as well as encoder 114, is appropriately made available tomicroprocessor 118 over data bus 116.

Outputs PA0-PA7 and PB0-PB7 are input/output ports of microprocessor 118which in the present embodiment are used only as output terminals whichare selectively accessed through a program control. Consider now thevarious outputs provided at these terminals. PA5-PA7 and PB5-PB7 arecoupled to the inputs of decoder 130. The signals at the outputs ofPA5-PA7 correspond respectively to two encoded bits designated as A0Aand A1A and an inverted enable signal, EA. Similarly, signals PB5-PB7include respectively two encoded bits A0B and A1B together with aninverted enable signal EB. These data bits and their respective enablesignals are thus coded according to conventional means into a pluralityof control signals as illustrated in FIG. 6. For example, the signals CLOFF HK, SET BSY, CL BSY, SET DWN, CL DWN, SET LO BAT and CL LO BAT whichwere described in connection with various status latches of FIG. 4 aregenerated by microprocessor 118 in combination with decoder 130. Thevarious latches are thus clocked and cleared at the appropriate timesunder software control as the status of call box 10 queried.

Outputs PA0-PA4 of microprocessor 118 are coupled to a control bus 132to respectively generate control signals A0-A4 whose use will be betterdescribed in connection with FIG. 10 in relation to the manipulation oftransceiver 44.

The output of PB1 of microprocessor 118, which is active low, is coupledto an inverter 134 whose output 136 is a signal, RLY ON, used to powerDarlington pair 94 in FIG. 5 in order to power up transceiver 44.

PA7, PB7, and PB1 are each pulled high through a resistor in the casewhere the lines float so that decoder 130 and the transceiver power uprelay are affirmatively maintained disabled unless clearly pulled activelow by an appropriate output on each of these lines.

The outputs of PB0-PB3 of microprocessor 118 are the signals, returndata transmit, R DATA T; receive data receive, R DATA R; true datareceive, T DATA R and inverted interrupt control, INT-CONT, which arespecific input and output control signals used to provide necessarycontrol functions for transceiver 44. Coupling directly to theinput/output ports PB0-PB3 of microprocessor 118 gives themicroprocessor the ability to directly respond to and to manipulate atransceiver if desired. However, in the present embodiment, thesecontrol ports are not specifically used for the Motorola transceiverillustrated.

Returning to FIG. 7, output PB1 of microprocessor 166, to be describedbelow, is also coupled to an input/output bus 138. PB1 is coupled frominput/output bus 138 to an inverter, generally denoted by referencenumeral 140. The inverted PB1 signal is applied to node 142 as thesignal, SVC (service), indicating that the transceiver has establishedradiotelephone contact with a ground station. The signal, SVC, is thencoupled to one of the inputs of encoder 114 and used as a conditionalsignal to generate the eight bit status words coupled from encoder 114to data bus 116.

The output PB7 of microprocessor 166, to be described below, issimilarly coupled to input/output bus 138 to an inverter generallydenoted by reference numeral 152. Output 154 from inverter 152 is theinverted signal, IN USE, which is used to signify that a call has beenplaced or is in process. Thus IN USE similarly can be used as aconditional signal in decoder 114 to prevent inappropriate transmissionof a status word to data bus 116.

Encoder 114 is also coupled to the two highest address bits A11 and A12from address bus 124 through a series of logic gates, generally denotedby reference numeral 144. More particularly, A12 is inverted by inverter146 and coupled together with address signal A11 to the inputs of NANDgate 148. The output of NAND gate 148 is logically combined in OR gate150 with the output of NAND gate 128, the inverted signal DS/R. Theoutput of OR gate 150 in turn is coupled to the inverted output enableterminal, OE, of encoder 114. Therefore, the output word from encoder114 is coupled to data bus 116 according to the logic provided by gates144. This logic prevents the placement of a status word on data bus 116at the same time that the program is being read from memory 120.

Turn now to FIG. 9 wherein signals A0-A4, generated on control bus 132by microprocessor 118 are converted into row and column key pad signalswhich can be understood by transceiver 44. The signal A4 on control bus132 corresponding to the output from terminal PA4 of microprocessor 118is an enable signal used to enable decoder 154. Decoder 154 is driven bythe control signals A2 and A3 corresponding respectively to terminalsPA2-3 of microprocessor 118. The output of decoder 154 are intermediateinverted decoding signals EA and EB. These signals are output inparallel to a second stage of two decoders 156 which have as additionalinputs, control bus signals A0 and A1 corresponding respectively toterminals PA0-1 of microprocessor 118. Ultimately the five control bitsA0-A4 will be converted into twelve key pad signals corresponding to thetwelve buttons on a telephone key pad corresponding to digits 0-9,* and#, and two additional related radiotelephone signals ON/OFF and volumecontrol, VOL CONT. Thus, bits A0-A3 represent sixteen possiblecombinations with a four-bit word which is decoded in two stages indecoders 154 and 156 and coupled as sixteen discrete output signals tothe inputs of analog switches 158-164. The A4 bit either disables allsixteen outputs or enables the one of sixteen outputs as designated bythe A0-A3 bits. Consider for example analog switch 164. The four inputsto analog switch 164 correspond to the key pad numerals 0-3. Withrespect to each of these numerals, two signals will need to be generatedin order to command transceiver 44, namely the row and columndesignations corresponding to key pad numbers 0-3. In particular,numeral 0 is located in the second column and fourth row. Therefore, thefirst two outputs of analog switch 164 correspond to column 2, row 4will be activated in response to activation of one of the inputs toanalog switch 164, such as E0. The pairs of outputs corresponding tonumerals 1, 2 and 3 are similarly activated. In the same manner theoutputs of analog switch 162 correspond to the row and column pairscorresponding to key pad numerals 4-7. Analog switch 164 similarlyincludes as its outputs key pad numerals 8 and 9, * and #. The outputsof analog switch 158 are peculiar to radiotelephones, which comprise afifth row. The fifth row on a radio telephone corresponds in the secondcolumn to the signal END and in third column to the signal SND. Includedas discrete signals are the control signals volume, VOL, and power, PWR,which are also referenced in FIG. 9 as the input/output signals on bus138 as VOL CONT and ON/OFF, respectively. Each of the row and columnsignals from switches 158-164 are active low and are appropriatelybuffered and coupled through diodes and resistors according toconventional principles as illustrated in FIG. 9 to I/O bus 138. By thismeans microprocessor 118 can be arbitrarily manipulate and controlradiotelephone transceiver 44.

Turning how to FIG. 10, a microprocessor 166, run by crystal controlledclock 168, allows signals received by transceiver 44 to the placesignals of the input/output bus 138. Microprocessor 166 interfaces thecircuitry and buses described above with the unique signals used bytransceiver 44 and to that extent is transceiver dependent. The signals,return data, R DATA; complementary data, C DATA; and true data, T DATAare signals specific to the Motorola transceiver 44 and are digitalsignals which are transmitted between transceiver 44 and the controller.

Each of these signals is coupled through appropriate logic circuits toinput ports of the microprocessor 166. For example, T DATA, an inputsignal to microprocessor 166, is coupled through an exclusive OR gate170 acting as a buffer since one input is held low. The output of gate170, which is T DATA, is also coupled to input port PB4 ofmicroprocessor 166. C DATA and buffered T DATA output from gate 170 areprovided as the inputs to exclusive OR gate 172. The output of gate 172is thus true whenever T DATA or C DATA are true but if in an idle statethey both go true, the output is false. Thus, the output of gate 172 istrue whenever data is being transmitted on the three wire bus and isfalse when the bus is in the idle state or reset state. The output ofgate 172 is provided as an input in turn to exclusive OR gate 174 whoseother input is coupled to an interrupt port PB3 of microprocessor 166.The output of gate 174 is coupled to the inverted interrupted terminal,INT, of microprocessor 166. This terminal will be active whenever datais being received from the transceiver. PB3 port acts as an internalacknowledgement signal. The output of gate 172 will be low when the datalink is the idle and will be high when it is busy. Therefore when PB3 ishigh, the inverted interrupt, INT, will go active low when data comesin. This will cause an interrupt to be executed in microprocessor 166 toenable it to receive data.

Finally, R DATA is similarly coupled to the output of transistor 178.Transistor 178 is in turn driven by output PB0, which is the data outputfrom microprocessor 166 to transceiver 44. An input of exclusive OR gate176 is also coupled to the output of transistor 178 and gate 176 acts asa buffer. Therefore, the output of buffer gate 176 is the signal, RDATA, which is applied to input port PB2 for the purposes of timing.

Consider briefly the timing protocol used on the three wire bus.Normally, the bus is in a reset state, i.e. C DATA and T DATA are bothfalse. When either one changes microprocessor 166 will be interrupted.The message appearing on the T DATA line contains a bus direction field,destination address field and data field. When microprocessor 166initiates communication, R DATA data will go low indicating a requestfrom processor 166. A logic unit in the transceiver will establish busdirection and will expect to receive a message on the R DATA line. Themessage then display on R DATA includes a source address field,destination field and data field. When the request for service isanswered by the transceiver, processor 166 will read the R DATA line andthe destination address field of the incoming message. Processor 166will place a first bit of R DATA on the line at the start of a datastate. During communication initiated by the transceiver the first databit will appear on the R DATA line after the bus goes from the resetstate to the date state. The remaining data will appear on the R DATAline during the idle state to data state transition period. The lastdata bit of the message will be held on the R DATA line a fewmicroseconds after the T DATA and C DATA lines have returned to thereset state to allow the bit to be read by the control unit. During acommunication initiated by processor 166, processor 166 will hold thefirst data bit on the R DATA line until T DATA and C DATA lines enter adata state at which time another bit is sent. At the occurrence of eachidle state, processor 166 will read the R DATA line through gate 176 andcompare it with what is being sent. If there is a conflict, processor166 will stop sending and vacate the bus. Processor 166 will requestservice again when the bus returns to the idle state.

Consider now the remaining output terminals of microprocessor 166. Theoutputs PC0-PC2 correspond to columns 3 through column 1 of the key padrespectively; outputs PA0-PA4 corresponding to rows 1-5 of the key padrespectively; and signals PB1 or SVC (service), and PB7 or IN USEdescribed above can be selectively generated coupled to input/output bus138. PA7 is a GAIN ADJ signal described below in connection with FIG. 11used to adjust audio signal strengths in the voice channel. PC3 iscoupled to a push button switch which can be manually operated by thecall box user to step up the audio strength of the received voicecommunication.

Turn now to FIG. 11 wherein the circuitry illustrative of audioprocessing is illustrated. The microphone input of hand set 40 iscoupled across terminals 180. The audio signal for the caller is therebycoupled through coupling capacitor 182 to an audio amplifier, generallyreferenced by numeral 184. The output of audio amplifier 184 is coupledthrough coupling capacitor 186 and provided as an output at node 188 asthe transmitted audio, TX AUDIO.

ON/OFF is a toggle signal on I/O bus 138 as described in FIG. 7 and issimilarly coupled through limiting resistor 190 to node 188 to overridethe transmitted audio signal according to microprocessor 166 to causethe transceiver to be turned on or off. Thus, grounding the on/off lineat I/O bus 138 causes the transceiver power to be turned on if it is offor to be turned off if it is on.

Similarly, audio volume control or a gain adjust signal, GAIN ADJ, isprovided from I/O bus 138 through signal PA7 of microprocessor 166. Thisis a gain adjust signal coupled through transistors 190 and 192 therebybiasing node 194 at the input side of audio capacitor 182 to a pointappropriate with the desired audio gain. Thus, the remote centralcontroller can advise call box 10 to turn up the microphone volume asneeded through the manipulation of the T, and C DATA signals coupled tomicroprocessor 166 which then appropriately generates the gain adjustsignal, PA7.

Similarly, the received audio from the remote central operator iscoupled terminal 196. Again, the received audio signal is coupledthrough an audio capacitor 198 into an audio amplifier generally denotedas reference numeral 200. The feedback of audio amplifier 200 in turn iscontrolled through the transistor 202 by means of the gain adjustsignal, GAIN ADJ, acting through the output transistor 190. Therefore,the received audio gain coupled to input 204 of differential amplifier206 can be remotely operator adjusted through gain adjust signal GAINADJ. The output of differential amplifier 206 in turn is coupled to theinput of a push/pull amplifier generally denoted by reference numeral208. The output of push/pull amplifier 208 is coupled as the opposinginput to differential amplifier 206 thereby maintaining the output 210of differential amplifier 206 at a continual maximum. The output ofpush/pull amplifier 208 is in turn resistively coupled through audiocapacitor 212 to the receiver or ear piece terminals 214 in hand set 40.

Solar array 34 is also coupled to battery 46 through controller 42 bymeans of a shunt regulator. The regulator is conventional and thus isnot further shown in the Figures. Coupling through the shunt regulatorprevents overcharging of battery 46 and thereby eliminates the potentialof any damage due to overvoltages or overcharging.

The circuitry now having been generally described in connection withFIGS. 4-9, turn to the flow diagram of FIG. 12 which illustrates thebasic operation of controller 42. Upon power-up as indicted by step 201,a master reset signal is generated to program control at step 203 toreset all chips within the circuit. This step generates any logic resetsignals required by the microprocessors 118 or 166 or any other logiccircuitry. In addition during this step the transceiver may execute anyinitial protocol operations. For example, in the case of the Motorolatransceiver of the illustrated embodiment, the best ground station orforward control channel is selected. Service is then established betweenthe selected forward control channel and the call box. The transceiveror microprocessor 118 then dials a preprogrammed telephone number andsends identifying codes which establish the call box's identity. Thesenumbers and codes are verified and then communications is selectivelyestablished on a reverse channel when appropriate. All this is protocolwhich is normally handled by the cellular transceiver and ground stationand do not strictly affect the operation of the invention as describedhere.

Thereafter, the outputs of each of the status chips are set to zero orinitialized at step 205. This corresponds to the generation of variousset signals shown as the output of decoder 130 and as described inconnection with the latches of FIG. 8.

Having cleared and set each of the status latches, processor 118 thenenters a self-test program to test the contents of memory 120 at step207. Each self-test program is checked a predetermined plurality oftimes at step 209. The test is repeated until it successfully passes ora timeout occurs. Upon successful self-testing of memory 120, processor118 will then read the various status signals as step 211 as describedin connection with FIG. 8. Should the pole down signal, DWN, forexample, be active as determined at step 213, processor 118 will thenenter a specialized down routine at step 215 to take whateverappropriate remedial action or reporting as is desired in the case thatthe call box has been run over or otherwise down on the ground.

After the down routine is completed, or there is no pole down situation,processor 118 then determines at step 216 whether the battery level islow. If the power is low, it enters a power subroutine at step 218 andperforms any remedial action necessary in response to low battery, suchas unconditionally disabling the transceiver 44. Again, after executionof the low power routine or if the power is adequate, microprocessor 118will then inquire at step 220 whether an emergency call is being placed.If an emergency caller is placing a call by lifting hand set 40 off thehook, an emergency call routine is entered at step 222 whereintransceiver 44 is powered up, a predetermined phone number is dialed ortransmitted, together with specific identifying information uniquelyidentifying call box 10. After the call is completed, the processingagain returns to step 210 where the status is reread.

If at step 220 an emergency call is not being placed, an inquiry will bemade at step 224 as to whether or not a predetermined time interval haspassed. In the illustrated embodiment call box 10 incorporates atwenty-four-hour flag. If a twenty-four-hour interval has not expiredsince step 224 was last queried, the processing will return to step 210.If on the other hand, twenty-four hours have elapsed since the lastquery at step 224, a call report status routine is entered at step 226.At step 226, microprocessor 118 will enter a predetermined subprogram totelephone the central processing unit regarding the status of call box10. Thus, every twenty-four hours or on any other arbitrary schedule,each call box will call the central processing center, identify itselfand report its current status or even a past log of activity.

Many modifications or alterations may be made by those having ordinaryskill in the art without departing from the spirit and scope of theinvention. For example, the operational routine described at FIG. 10 isillustrative only and any other means could be arbitrarily programmedinto execution. It is to be expressly understood that a differentcellular transceiver, such as an OKI model UM 1043B manufactured by OKIElectric Industries Co. Ltd of Atlanta, Ga., could be easily substitutedfor the illustrated Motorola transceiver with appropriate modificationsto accommodate the substitution according to well know designprinciples.

Furthermore, it should be noted in connection with the circuit diagramsof FIGS. 4-9 that call box 10 incorporates a digital address bus, databus, control bus and I/O bus. Therefore, it is entirely within the scopeof the art that such generalized bus structures can be employed withother digital circuitry to expand the operational capacities of call box10. For example, a slow scan video circuit can be appropriately coupledto the buses if desired to provide visual information of trafficconditions at selected points. In addition, a data telemetry inputsubcircuit can similarly be coupled to the buses of call box 10 toallow, for example, for the transmission of digital medical data byparamedical emergency teams who may be attending an accident victim nearthe site of a call box. Such emergency medical data could beradio-telemetered from the accident site to the nearest call box whichwould then retransmit to the nearest hospital without the necessity oflifting hand set 40 off the hook or other direct wire coupling to thecall box. The call box could similarly be time share with environmentalsensing and reporting systems. Virtually any device which could benefitfrom a remote communications device could be easily combined andaccommodated by the open bus structure of the invention. Theadaptability of the invention is even further enhanced when it isrealized that interactive digital and voice communications isfacilitated through call box 10.

Therefore, the illustrated embodiment must be understood as beingprovided only for the purposes of example and clarity and not as alimitation of the invention as defined in the following claims.

I claim:
 1. A system for emergency call box service comprising:aplurality of emergency call boxes, wherein each call box furthercomprises a controller, a cellular transceiver coupled to saidcontroller, a battery coupled to said controller for providing power tosaid controller and transceiver, and means for generating power coupledto said controller for recharging said battery; and a cellulartelecommunications subsystem in radio-telecommunication with each ofsaid plurality of emergency call boxes.[.,.]..Iadd.; .Iaddend. saidcellular transceiver being remotely .[.programmable.]..Iadd.controllable .Iaddend. said controller for .[.programming.]..Iadd.controlling .Iaddend.operation of said cellular transceiver inresponse to information .[.receivied.]. .Iadd.received .Iaddend.fromsaid cellular telecommunications subsystem wherein said controllerfurther comprises means for receiving and processing information toinitiate .[.operations in said controller.]. .Iadd.action at the callbox.Iaddend., whereby said plurality of emergency call boxes can beinstalled which are capable of arbitrarily .[.programmable.]..Iadd.controllable .Iaddend.interactive operations.
 2. The system ofclaim 1 further comprising interoffice local telephone exchanges coupledto said plurality of call boxes wherein communication between saidcellular telecommunication subsystem and said plurality of call boxes isselectively coupled through said interoffice local telephone exchanges.3. An emergency roadside call box comprising:a controller means forreceiving remotely originated information; a remotely .[.programmable.]..Iadd.controllable .Iaddend.cellular transceiver coupled to andcontrolled by said controller, operation of said cellular transceiverbeing initiated at least in part by said remotely originated informationreceived by said controller .Iadd.to produce action at the callbox.Iaddend.; a battery for powering said controller coupled to saidcontroller and transceiver; and means coupled to said controller forrecharging said battery.
 4. The call box of claim 3 further comprising asubcircuit for monitoring a user request for emergency transmission. 5.The call box of claim 3 comprising a subcircuit for monitoring presenceof a communication transmitted to and from said call box.
 6. The callbox of claim 3 further comprising means for selectively communicating aplurality of parameters of said call box to an off-site recipient. 7.The call box of claim 3 wherein said controller comprises means ofconserving power from said battery when an emergency communication isnot desired.
 8. A method in an emergency roadside call box, said callbox being battery powered and coupled through a radio-telecommunicationlink to a cellular telecommunication system and communicationapplications processor, said method comprising the steps of:reading aplurality of call box status parameters at a plurality of call boxes;sending information from said communication applications processor orcellular telecommunication system to selectively .[.perform a remedialroutine.]. .Iadd.initiate action at the call box location .Iaddend.inresponse to said step of reading said plurality of status parametersdependent upon the condition of each corresponding parameter in order torender said call box operational; selectively receiving said informationat said plurality of call boxes .Iadd.and initiating said action inresponse thereto.Iaddend.; selectively entering an emergency callroutine wherein a cellular telecommunications transceiver within saidcall box is powered up and bidirectional voice communication isestablished through said cellular telecommunication system to saidcommunication applications processor, whereby remotely powered emergencycall boxes in radiotelecommunication with said communicationapplications processor are operationally maintained.
 9. The method ofclaim 8 further comprising the step of selectively reporting saidplurality of status parameters from each said call box through saidcellular telecommunication system to said communication applicationsprocessor.
 10. An apparatus in combination with a cellularradio-telephone for generating information compatible with said cellularradiotelephone in an emergency call box comprising:first means fordetermining a plurality of status conditions relating to said emergencycall box; second means for controlling power usage of said.[.emerency.]. .Iadd.emergency .Iaddend.call box to .[.minimized.]..Iadd.minimize .Iaddend.power usage; and third means for processing saidstatus conditions determined by said first means and responsive to atleast said second means, said third means for selectivelybidirectionally communicating cellular radiotelephone compatiblesignals, said third means being coupled to said first and second meansand to said cellular radiotelephone, said third means being remotely.[.programmable.]. .Iadd.controllable .Iaddend.to selectively processsaid status conditions and to selectively communicate said cellularradiotelephone compatible signals and .[.selectively communicate saidcellular radiotelephone compatible signals and.]. selectively .[.operatesaid apparatus.]. .Iadd.perform actions at the call box .Iaddend.inresponse thereto.